The findings suggest that patients should be screened for frailty before kidney transplantation, and that those identified as frail need to be closely monitored after their transplant, the study authors said.

The researchers assessed frailty in 537 patients around the time of their kidney transplant. Five years later, survival rates were 91.5 percent for non-frail patients, 86 percent for intermediately frail patients, and 77.5 percent for frail patients, according to the study published online Oct. 30 in the American Journal of Transplantation.

"Our results suggest that frail kidney transplant recipients are at twice the risk of mortality even after accounting for important recipient, transplant and donor characteristics," Mara McAdams-DeMarco, from the Johns Hopkins University School of Public Health and School of Medicine, said in a journal news release.

It's easy to assess a patient's frailty before transplantation to identify those who require close monitoring, she noted.